Hot blower fan lead

[tberk@mindspring.com (T Berk)]

Cmr446@cs.com wrote:
> 
> Curt
>   I've been thinking of relaying the fan motor since this happened. Would you
> relay from the power lead itself, running the relay all the time the car is
> on, or from the fan switch, requiring one relay for each speed?
> 
> Carl
> 77rocco
> 89fox
> 


Here are my thoughts:

- Relay has four posts. (maybe 5- but one is doubled in this case)

- One is power in and another power out, two more for the trigger's in
and out, (this out going to ground).

- I would run a power wire straight from the battery or a power block
(like the big time radio/amp boys do) and place a fuse real close to the
battery. This is your Terminal 30 constant source of 12v. Conversely you
could run it from the fuse box but I am of a mind to lighten the current
running through my twenty year old fuse box.

- Other side of the relay would run to the fan switch's big red wire. In
fact disconnect the wire at it's other end and run it straight ot the
relay. Or replace it with a newer, better wire. Red or Black would be
nice.

That takes care of the hot 12v, it runs from the battery through a fuse
and then to the speed switch onto the fan motor.

-  The relay now needs a trigger signal. For this we source Switched
12v, it lives in many places. One of them is the fuse box, another is
coming back to said box from the Ign switch.  This Terminal 15 power is
ON when Ign is on, Off when the key is out and OFF when the Starter is
running. (Mostly).

- Lastly the relay needs brown wire to take the trigger current to
ground, fancy dancy location would be the ground rose under the dash,
near the steering column. Looks stock that way. Of course this depends a
lot on where your relay is located. If in the engine bay use your wits.


It's a long one, full of words but hth,
TBerk